Index: llvm/include/llvm/IR/ConstantRange.h
===================================================================
--- llvm/include/llvm/IR/ConstantRange.h
+++ llvm/include/llvm/IR/ConstantRange.h
@@ -526,6 +526,11 @@
   /// \p IntMinIsPoison is false.
   ConstantRange abs(bool IntMinIsPoison = false) const;
 
+  /// Calculate absolute value range. If the original range contains zero, then
+  /// the resulting range will be bounded if and only if \p ZeroIsPoison is
+  /// false.
+  ConstantRange ctlz(bool ZeroIsPoison = false) const;
+
   /// Represents whether an operation on the given constant range is known to
   /// always or never overflow.
   enum class OverflowResult {
Index: llvm/lib/IR/ConstantRange.cpp
===================================================================
--- llvm/lib/IR/ConstantRange.cpp
+++ llvm/lib/IR/ConstantRange.cpp
@@ -945,6 +945,7 @@
   case Intrinsic::smin:
   case Intrinsic::smax:
   case Intrinsic::abs:
+  case Intrinsic::ctlz:
     return true;
   default:
     return false;
@@ -976,6 +977,12 @@
     assert(IntMinIsPoison->getBitWidth() == 1 && "Must be boolean");
     return Ops[0].abs(IntMinIsPoison->getBoolValue());
   }
+  case Intrinsic::ctlz: {
+    const APInt *ZeroIsPoison = Ops[1].getSingleElement();
+    assert(ZeroIsPoison && "Must be known (immarg)");
+    assert(ZeroIsPoison->getBitWidth() == 1 && "Must be boolean");
+    return Ops[0].ctlz(ZeroIsPoison->getBoolValue());
+  }
   default:
     assert(!isIntrinsicSupported(IntrinsicID) && "Shouldn't be supported");
     llvm_unreachable("Unsupported intrinsic");
@@ -1667,6 +1674,45 @@
                                     APIntOps::umax(-SMin, SMax) + 1);
 }
 
+ConstantRange ConstantRange::ctlz(bool ZeroIsPoison) const {
+  if (isEmptySet())
+    return getEmpty();
+
+  APInt Zero = APInt::getZero(getBitWidth());
+  if (ZeroIsPoison && contains(Zero)) {
+    // ZeroIsPoison is set, and zero is contained. We discern three cases, in
+    // which a zero can appear:
+    // 1) Lower is zero, handling cases of kind [0, 1), [0, 2), etc.
+    // 2) Upper is zero, wrapped set, handling cases of kind [3, 0], etc.
+    // 3) Zero contained in a wrapped set, e.g., [3, 2), [3, 1), etc.
+
+    if (getLower().isZero()) {
+      if ((getUpper() - 1).isZero()) {
+        // We have in input interval of kind [0, 1). In this case we cannot
+        // really help but return empty-set.
+        return getEmpty();
+      }
+
+      // Compute the resulting range by excluding zero from Lower.
+      return ConstantRange(
+          APInt(getBitWidth(), (getUpper() - 1).countLeadingZeros()),
+          APInt(getBitWidth(), (getLower() + 1).countLeadingZeros() + 1));
+    } else if ((getUpper() - 1).isZero()) {
+      // Compute the resulting range by excluding zero from Upper.
+      return ConstantRange(
+          Zero, APInt(getBitWidth(), getLower().countLeadingZeros() + 1));
+    } else {
+      return ConstantRange(Zero, APInt(getBitWidth(), getBitWidth()));
+    }
+  }
+
+  // Zero is either safe or not in the range. The output range is composed by
+  // the result of countLeadingZero of the two extremes.
+  return getNonEmpty(
+      APInt(getBitWidth(), getUnsignedMax().countLeadingZeros()),
+      APInt(getBitWidth(), getUnsignedMin().countLeadingZeros() + 1));
+}
+
 ConstantRange::OverflowResult ConstantRange::unsignedAddMayOverflow(
     const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())
Index: llvm/test/Analysis/LazyValueAnalysis/lvi-for-ctlz.ll
===================================================================
--- /dev/null
+++ llvm/test/Analysis/LazyValueAnalysis/lvi-for-ctlz.ll
@@ -0,0 +1,108 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=jump-threading -S | FileCheck %s
+
+; Ensures that LazyValueInfo correctly propagates the constant range lattice values to ctlz intrinsic.
+
+; Constant range value may be bounded on [28,31] interval,
+; as forward.0 is taken only if %val is within [1,9].
+define i32 @test_ctlz_1(i32 %val) {
+; CHECK-LABEL: @test_ctlz_1(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[ADD:%.*]] = add i32 [[VAL:%.*]], -1
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[ADD]], 9
+; CHECK-NEXT:    br i1 [[COND_0]], label [[FORWARD_0:%.*]], label [[FORWARD_1:%.*]]
+; CHECK:       forward.0:
+; CHECK-NEXT:    [[RET_VAL_0:%.*]] = tail call i32 @llvm.ctlz.i32(i32 [[VAL]], i1 true), !range [[RNG0:![0-9]+]]
+; CHECK-NEXT:    ret i32 [[RET_VAL_0]]
+; CHECK:       forward.1:
+; CHECK-NEXT:    [[COND_1:%.*]] = icmp ugt i32 [[VAL]], 20
+; CHECK-NEXT:    [[RET_VAL_1:%.*]] = select i1 [[COND_1]], i32 10, i32 0
+; CHECK-NEXT:    ret i32 [[RET_VAL_1]]
+;
+entry:
+  %add = add i32 %val, -1
+  %cond.0 = icmp ult i32 %add, 9
+  br i1 %cond.0, label %forward.0, label %forward.1
+
+forward.0:                                        ; preds = %entry
+  %ret_val.0 = tail call i32 @llvm.ctlz.i32(i32 %val, i1 true), !range !0
+  ret i32 %ret_val.0
+
+forward.1:                                        ; preds = %entry
+  %cond.1 = icmp ugt i32 %val, 20
+  %ret_val.1 = select i1 %cond.1, i32 10, i32 0
+  ret i32 %ret_val.1
+}
+
+@g_unsigned_char = global i8 0
+
+; Constant range value may be bounded on [23,32] interval, as it takes
+; the sum of %val, which is within [0, 10], and g_unsigned_char, which is
+; within [0, 255], and ZeroIsPoison is set to false.
+define i32 @test_ctlz_2(i32 %val) {
+; CHECK-LABEL: @test_ctlz_2(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[VAL:%.*]], 10
+; CHECK-NEXT:    br i1 [[COND_0]], label [[FORWARD_0:%.*]], label [[FORWARD_1:%.*]]
+; CHECK:       forward.0:
+; CHECK-NEXT:    [[LOAD:%.*]] = load i8, ptr @g_unsigned_char, align 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[LOAD]] to i32
+; CHECK-NEXT:    [[ADD:%.*]] = add nuw nsw i32 [[ZEXT]], [[VAL]]
+; CHECK-NEXT:    [[RES:%.*]] = tail call i32 @llvm.ctlz.i32(i32 [[ADD]], i1 false), !range [[RNG0]]
+; CHECK-NEXT:    br label [[FORWARD_1]]
+; CHECK:       forward.1:
+; CHECK-NEXT:    [[RET_VAL:%.*]] = phi i32 [ [[RES]], [[FORWARD_0]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i32 [[RET_VAL]]
+;
+entry:
+  %cond.0 = icmp ult i32 %val, 10
+  br i1 %cond.0, label %forward.0, label %forward.1
+
+forward.0:                                        ; preds = %entry
+  %load = load i8, i8* @g_unsigned_char
+  %zext = zext i8 %load to i32
+  %add = add nuw nsw i32 %zext, %val
+  %res = tail call i32 @llvm.ctlz.i32(i32 %add, i1 false), !range !0
+  br label %forward.1
+
+forward.1:                                         ; preds = %entry, %forward.0
+  %ret_val = phi i32 [ %res, %forward.0 ], [ 0, %entry ]
+  ret i32 %ret_val
+}
+
+; Same as test_ctlz_2, this time with ZeroIsPoison set to true.
+; Hence, constant range value may be unknown.
+define i32 @test_ctlz_3(i32 %val) {
+; CHECK-LABEL: @test_ctlz_3(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    [[COND_0:%.*]] = icmp ult i32 [[VAL:%.*]], 10
+; CHECK-NEXT:    br i1 [[COND_0]], label [[FORWARD_0:%.*]], label [[FORWARD_1:%.*]]
+; CHECK:       forward.0:
+; CHECK-NEXT:    [[LOAD:%.*]] = load i8, ptr @g_unsigned_char, align 1
+; CHECK-NEXT:    [[ZEXT:%.*]] = zext i8 [[LOAD]] to i32
+; CHECK-NEXT:    [[ADD:%.*]] = add nuw nsw i32 [[ZEXT]], [[VAL]]
+; CHECK-NEXT:    [[RES:%.*]] = tail call i32 @llvm.ctlz.i32(i32 [[ADD]], i1 true), !range [[RNG0]]
+; CHECK-NEXT:    br label [[FORWARD_1]]
+; CHECK:       forward.1:
+; CHECK-NEXT:    [[RET_VAL:%.*]] = phi i32 [ [[RES]], [[FORWARD_0]] ], [ 0, [[ENTRY:%.*]] ]
+; CHECK-NEXT:    ret i32 [[RET_VAL]]
+;
+entry:
+  %cond.0 = icmp ult i32 %val, 10
+  br i1 %cond.0, label %forward.0, label %forward.1
+
+forward.0:                                        ; preds = %entry
+  %load = load i8, i8* @g_unsigned_char
+  %zext = zext i8 %load to i32
+  %add = add nuw nsw i32 %zext, %val
+  %res = tail call i32 @llvm.ctlz.i32(i32 %add, i1 true), !range !0
+  br label %forward.1
+
+forward.1:                                         ; preds = %entry, %forward.0
+  %ret_val = phi i32 [ %res, %forward.0 ], [ 0, %entry ]
+  ret i32 %ret_val
+}
+
+declare i32 @llvm.ctlz.i32(i32, i1 immarg) nounwind willreturn
+
+!0 = !{i32 0, i32 33}
Index: llvm/unittests/IR/ConstantRangeTest.cpp
===================================================================
--- llvm/unittests/IR/ConstantRangeTest.cpp
+++ llvm/unittests/IR/ConstantRangeTest.cpp
@@ -2397,6 +2397,21 @@
       });
 }
 
+TEST_F(ConstantRangeTest, Ctlz) {
+  TestUnaryOpExhaustive([](const ConstantRange &CR) { return CR.ctlz(); },
+                        [](const APInt &N) {
+                          return APInt(N.getBitWidth(), N.countLeadingZeros());
+                        });
+
+  TestUnaryOpExhaustive(
+      [](const ConstantRange &CR) { return CR.ctlz(/*ZeroIsPoison=*/true); },
+      [](const APInt &N) -> std::optional<APInt> {
+        if (N.isZero())
+          return std::nullopt;
+        return APInt(N.getBitWidth(), N.countLeadingZeros());
+      });
+}
+
 TEST_F(ConstantRangeTest, castOps) {
   ConstantRange A(APInt(16, 66), APInt(16, 128));
   ConstantRange FpToI8 = A.castOp(Instruction::FPToSI, 8);